Effects of ethanol on the in situ synthesized Cu/SiO2 catalyst: Texture, structure, and the catalytic performance in hydrogenation dimethyl oxalate to ethylene glycol

The Cu/SiO2 catalysts were in situ synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS) in one phase solution using ethanol as co-solvent or TEOS/H2O two phases solution, followed by the precipitation of copper on SiO2 by ammonia evaporation. In the hydrogenation of dimethyl oxalate, the catalyst prepared by one phase hydrolysis exhibited higher activity and ethylene glycol (EG) selectivity at lower temperature than that of two phases due to its larger BET surface area and multimodal pore distribution. At 488–503 K, the catalyst prepared in one phase solution with water/ethanol (W/E) volume ratio of 3:1 exhibited 90–95% EG selectivity, while catalyst prepared by two phase hydrolysis reached 90% EG selectivity only at 498–503 K.